[Effect of sevoflurane postconditioning on spinal cord ischemia reperfusion injury via the release of oxygen free radicals in rabbits].

OBJECTIVE: To investigate whether postconditioning with sevoflurane could alleviate spinal cord ischemia reperfusion injury in rabbits, and whether the beneficial effect is dependent on oxygen free radicals. METHODS: In Experiment 1, 48 male New Zealand white rabbits were randomly assigned to six groups (n=8 each). Animals in the sham group only underwent sham-operation. Animals in the control group underwent spinal cord ischemia for 20 min without postconditioning. Animals in 02 postconditioning group (Group O2) inhaled 100% O2 from 5 min before reperfusion and lasted 13 min. Animals in sevoflurane postconditioning groups (Group Sevo0.5, Sevo1.0 and Sevo1.5) inhaled 0.5, 1.0, 1.5 minimum alveolar concentration (MAC) sevoflurane in 100% O2 from 5 min before reperfusion and lasted 10 min, then inhaled 100% O2 for 3 min to wash out the remaining sevoflurane. In Experiment 2, 36 male New Zealand White rabbits were randomly assigned to four groups (n=9 each). Animals in O2 and Sevo groups received normal saline (5 ml/kg intravenously) 1 h before postconditioning with 100% O2 and 1.0 MAC sevoflurane, respectively. In the DMTU + Sevo and DMTU + O2 groups, 5 ml/kg of 10% dimethylthiourea (DMTU, a potent oxygen free radical scavenger, dissolved in saline) was administered intravenously at the same time. Spinal cord ischemia was induced by an infrarenal aorta clamping for 20 min. Forty-eight hours after reperfusion, hind-limb motor function and histopathology of the spinal cord were examined in a blinded fashion. RESULTS: (1) The neurologic and histopathologic outcomes in the sevoflurane postconditioning groups were better than those in the control group (P < 0.05), the histopathologic outcomes in Sevo1.0 group were better than that in Sevo0.5 and Sevo1.5 groups (P < 0.05). (2) The neurologic and histopathologic outcomes in Sevo, DMTU + Sevo and DMTU + O2 groups were better than those in the O2 group (P < 0.05), the histopathologic outcomes in Sevo group were better than that in the DMTU + Sevo and DMTU + O2 groups (P < 0.05). CONCLUSIONS: Our study demonstrates that sevoflurane postconditioning against spinal cord ischemia injury via the release of oxygen free radicals in rabbits.